1. Field of the Invention
This invention relates to a laser cathode production process. More particularly, this invention pertains to a process for producing a laser cathode of the type that includes a substantially spherical glass or glass-ceramic base of predetermined thermal properties with an aluminum or aluminum alloy interior coating.
2. Description of the Prior Art
Laser cathodes of the type that include a basic element of glass or glass-ceramic of domed shape and semispherical dome curvature are described in West German patent application No. DE-A1-33 46 232. Such cathodes are most commonly employed in laser amplifiers and oscillators. In operation, a negative potential is applied to the laser cathode and it is bombarded by the positively charged ions (e.g. He.sup.+ and Ne.sup.+) that combine with the electrons supplied to the (oxidized) inner surface of the cathode as a result of the negative potential. As a result, uncharged gas molecules are again formed. The impacts of the ions with the cathode's surface produces surface sputtering processes and absorption of light inert gases (e.g., He and Ne). Such processes reduce the service life of the cathode and, of course, that of the entire laser arrangement as such sputtering effects continually contaminate the laser gases.
In prior coating processes, the cathode became naturally oxidized in an unreproducible way when the coating unit was opened after coating. Attempts were made to enhance cathode service life by post-oxidation of the applied Al layer (e.g., by introduction of pure oxygen and an oxygen/inert gas mixture). Such efforts have realized only limited success. The mirrors of the laser arrangement are adversely affected by such oxygen charging processes.